Use a single cros_toolchain tarball for ChromeOS build

It's stored in our GS bucket, so we won't need two sets of credentials.
(SkipBuildbotRuns) since this isn't in use.

Review URL: https://codereview.chromium.org/17608003

git-svn-id: http://skia.googlecode.com/svn/trunk@9743 2bbb7eff-a529-9590-31e7-b0007b416f81
2 files changed